You shouldn't break the bead on the 16 inch until you throw them out. Pull the rim half's apart and block them with wood blocks until you can pull the tube out one side at a time.
I posted a thread on that last year i think.
20 inch rims of mine have come apart very easy compared to the 16's.
this thread
http://www.mapleleafup.net/forums/sh...ad.php?t=18748